High-temperature deformation behavior and microstructure evolution of TiBw/Ti6Al4V composites during hot shear-compression deformation

Hot shear-compression deformation (HSCD) of in situ TiBw/Ti6Al4V composites with network architecture was conducted at variant temperature from 1123 to 1223 K and strain rate from 10⁻³ to 10⁻¹ s⁻¹ by using shear-compression specimens (SCS). According to equivalent stress and strain curves, the activation energy was calculated to be 631.1 kJ/mol in α+β phase region. In addition, the appearance of shear bands in the gage region was a typical evidence that shear was the major deformation during HSCD. Furthermore, dynamic recovery (DRV) and dynamic recrystallization (DRX) occurred in the shear bands, resulting in a decrease in flow stress. The mechanism of DRX in α+β phase region included the continuous rotation of substructure which was attributed to continuous dynamic recrystallization (cDRX) and formation of fine equiaxed grains which experienced nucleation and growth was attributed to discontinuous dynamic recrystallization (dDRX). Additionally, the existence of TiBw could promote the process of DRX by providing high density dislocations and nucleation sites.